Our specific approaches to the understanding of the biology and biochemistry of influenza viruses include, 1) further amino acid sequencing of the Heql hemagglutinin to seek additional confirmatory evidence of significant variation of its heavy chain from that found with human subtype viruses, 2) extension of the screening process for detection of virion transcriptase activity to ts mutants from all of our complementation groups. It will be particularly interesting to see the results of this analysis of group III mutants as they apparently synthesize no cRNA in vivo at non-permissive temperatures. (If more than one gene product is required for the synthesis of cRNA the specific role of each in this process will be pursued), 3) studies of cellular immunity are only preliminary and they will be pursued by further studies of adoptive immunization of mice with T cell populations, 4) the immunogenicity in man of isolated influenza viral neuraminidase has never been investigated and this will be a key question to answer during the forthcoming year in studies to be conducted by other investigators, 5) we shall continue our efforts to identify and isolate the receptor destroying enzyme of influenza C virus and also to confirm the presence of a segmented RNA genome in the virus. Also the establishment of a plaque forming system will be necessary for the initiation of genetic studies of the virus. BIBLIOGRAPHIC REFERENCES: K. Tobita and E. D. Kilbourne. Structural polypeptides of antigenically distinct strains of influenza B virus, Arch. Virol., 47,367, (1975). E. D. Kilbourne, P. Palese and J. L. Schulman. Inhibition of viral neuraminidase as a new approach to the prevention of influenza in Perspectives in Virology, Vol. IX, Academic Press, New York (1975) (M. Pollard, ed.).